Posted: 1/16/2009 7:04:56 AM EDT
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Guys,
Long story short, we are replacing the ceiling in our garage due to one of my daughter's friends causing a flood in the bathroom above. Our garage is roughly 960 sq ft. Now that the drywall is off, I can see that my original builder used R-19 batting type insulation. The problem is that the gap between the insulation and the sub-floor above is more than a foot. As you can imagine, the playroom (which is above the garage) is way hotter than the rest of the house in summer, and way colder in winter. We want to remedy this. Is it reasonable and effective to add another layer of R-19 batting insulation to the existing insulation? That is what is being suggested. How effective would two layers of R-19 be vs. Icynene? |
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if i understand your situation, you're talking about doubling up the insulation that would be in the floor of the bonus room. this will not really help the temperature fluctuation of the bonus room, since most of your heat is going to be lost or gained through the roof. it would be much more effective to add insulation above the ceiling /to the walls of the bonus room. foamed-in-place is probably your best bet.
-matt |
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Cold in the winter and hot in the summer could be a multitude of issues. Beefing up the insulation in the floor of the bonus room may be an idea and certainly would not hurt, but I would also look at where the thermal "mass" that is adversely affecting the bonus room is coming from. Part of this also depends where in the country you are.
I would take a guess that your house has one thermostat stuck downstairs in the family room and that your bonus room has a conventional roof over it. Additionally, the ducting to your bonus room is probably poorly sized and the thermal characteristics of the bonus room are probably too wildly different from the rest of the house. While you have the ceiling of the garage down, I would certainly beef up the insulation to R38, but also add a reflective thermal barrier such as "Reflectix" with an air gap between the insulation and the ceiling of the garage. Mor eimportantly though, I would also use reflectix in the attic space (close to the roof deck) above the bonus room, and likely seek to add extra insulation above the ceiling of the bonus room. R38 would be fine, but you'll probbaly need to install baffles to avoid blocking your soffits. You should also check the ventilation in the roof-space as again, heat buildup in the day will hammer down on the bonus room. Additional vents or an attic fan can help, but the reflectix will often eliminate the need for that. Reflectix will make a big difference in the summer. My attic went from typically hitting 140 degrees in the summer when it was 95 outside, to staying within about 10 degrees of ambient now that the reflectix is in. A final option is to zone your HVAC to have automatic control over where the air actually goes. 5 years ago I retrofitted a Honeywell Envirazone 4-zone system to my system when we replaced the furnace. It certainly makes a huge difference to comfort across the house. Cheers 7.62 |
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per 2006 international energy conservation code:
TN is a climate zone 4 with the following exsceptions: chester, croket, dryer, fayette, hardeman, hardin, haywood, henderson, lake, lauderdale, madison, mcnairy, shelby and tipton which are all climate zone 3. Per table 402.1.1 Insulation requirements Zone 4: wood framed walls: R-13 cealing: R-38 zone 3: wood framed walls: R-13 cealing: R-30 just a quick guess but I believe this is your current code ETA scratch that, TN IECC is not adopted state wide, you will have to see what the current regs say for your county |
| Thanks for all the advice so quickly. Definitely jumping up to R-38 in the ceiling, probably going with Reflectix also. We probably need to and will add a few more inches of blown cellulose in the attic. We'll tackle a zone controlled HVAC in the spring or summer. |